Do you understand the literal meaning? You can literally extend it: when a person without shoes meets a person without feet, how will he feel? If you don't have shoes, you can still walk normally with your feet. Maybe one day, when you find a good job, you may even wear shoes. What about the man with no feet? He'll never put on his shoes.

This sentence means that there will never be the most unlucky person in the world. Our difficulties may seem to some people to be great happiness. So we should be optimistic and firmly believe that the pain will eventually pass.